My apologies for not getting back to you on your request sooner. I have attached examples of fish passage facilities that have been used at sites similar to the Mirror Pond site. The first two pictures are of “vertical slot” fishways, which would be my first choice given the fish species and hydrology in the Deschutes at that site. This style of fishway allows fish to “swim through” rather than jump over each step of the ladder, and tends to perform well on larger river systems. For a dam structure that is 13-15 feet tall I would expect a vertical slot with at least 17 to 30 steps.
The second two pictures are of pool and weir fishways, which require fish to leap over each step. These pass fish rather well, especially in low water situations but require a little more maintenance versus the vertical slot because the “weirs” need to be adjusted as the river flows go up and down. Vertical slots are self adjusting. Given fish species in the Deschutes the max “jump height” at each step would be 6 inches, therefore a pool and weir solution would have anywhere from 26-30 steps to provide adequate passage over the dam at Mirror Pond.
That is just some basic information and assumptions on possible fish passage solutions, and when the time comes for passage the site will be thoroughly poured over to ensure the correct solution is selected to provide fish passage. If you have any questions, please let me know.
Thank you for your interest and community involvement, take care.
Assistant Fish Passage Coordinator
Oregon Department of Fish and Wildlife